There are two types of mouth rinses: cosmetic rinses that suppress bad oral smell for the period and leave a pleasant after taste, and the other is therapeutic mouthwash that kills the agents that cause the issues. Cosmetic rinses do not have any bacterial action and there is no benefit beyond the temporary effect, while therapeutic mouthwashes contain a different chemical agent that is capable of killing the bacteria that is present in the mouth and cause plaque formation, gingivitis, caries, and bad breath. Different mouth rinses would have different reagents depending on the objective.
Mouthwashes are formulated for specific purposes also. After tooth extraction especially third molar one of the difficult condition is the dry socket or technically called Alveolar Osteitis. This occurs when the blood clot that is formed in the socket gets dislodged. The real reason for the clot dislodging is not known. It is thought that bacterial action causes the decomposing of the colt. This causes intense pain at the site of extraction for two to three days after the extraction. Studies have shown the use of chlorhexidine without antibiotic is effective in preventing the clots from dislodging from the socket. The gel formulation was found to be marginally more effective. It was found to discolor teeth, denture and tongue and altered taste.
Mouthwash formulations for control of gingivitis and plaque antimicrobial agents like essential oils, chlorhexidine, and cetylpyridinium have been found to be effective. Chlorhexidine is found to be more efficacious in plaque control aspect. Cetylpyridinium and chlorhexidine were found to stain teeth, restorations and tongue brown.
Fluoride ions in mouth wash were found to be effective in preventing dental decay irrespective of other sources of fluoride like fluoridated drinking water or toothpaste in recent reviews.
Mouth rinses for pain relief usually contain topical anesthetics like lidocaine and dyclonine hydrochloride.
Mouth rinses are formulated for whitening teeth. These mouthwashes contain carbamide peroxide or hydrogen peroxide as active principle. These are found to be effective in removing extrinsic stains. Hydrogen peroxide of 1.5% to 2% used for 12 weeks gave the same effect as 10% carbamide peroxide gel used for 2 weeks.
Mouthwashes are formulated for relieving Xerostomia or dry mouth. Dry mouth increases the risk of caries. Since alcohol dries the oral mucosa it is best to avoid the use of mouthwashes containing alcohol. Mouthwashes containing cellulose derivatives, animal mucins, and certain enzymes act and feels like saliva. They do afford a measure of relief to the symptoms.
Since alcohol and tobacco use have potential risk for cancers of head and neck there were concerns over using alcohol in mouthwashes. Recent reviews and Meta-analyses have not shown any relationship between the use of alcohol-containing mouthwashes and increased risk for oral and neck cancers.
Mouth rinses are used for suppressing bad oral odor. Generally, oral malodor is due to the breaking down of food, bacteria and plaque produce volatile sulfur compounds. It is these sulfur compounds that give mouth the foul odor. Cosmetic mouthwashes can mask these odors for a period and leave a pleasant flavor. However, mouth rinses that contain bactericides like chlorhexidine, essential oils, chlorine dioxide and agents like zinc salts, ketone, terpene and ionone that inhibit the odor creating compounds are found to be effective for longer periods.